The electrochemical oxidation of oxalic acid (OA) has been studied, in acidic media, at Ti/PbO2, highly boron-doped diamond (BDD), Pt, Au and Ti/IrO2-Ta2O5 electrodes, by both cyclic voltammetry and bulk electrolysis. The anodic oxidation of OA has clearly shown that the electrode material is an important parameter when optimizing such processes, since the mechanism and the products of several anodic reactions are known to depend on the anode material. OA was oxidized at several substrates to CO2 with different results; however, higher current efficiencies were obtained at Ti/PbO2, Pt and BDD. At Ti/PbO2, the carboxylic groups are expected to strongly interact with the Pb-(IV) sites and the hydroxyl radical formed on/at the electrode surface. In some cases, complex interactions exist between the organic substrate and the electrode surface, as confirmed by the oxidative behavior of OA at the Pt electrode. (C) 2004 Elsevier Ltd. All rights reserved.